Keylever touch control with compensating means directly proportional to keylever touch



1 l 1 t 1 e 9 m V 0 5 T 4 C S E any 3 e h S 2 5, 1968 s. o. CAPPOTTO KEYLEVER TOUCH CONTROL WITH COMPENSATING MEANS DIR PROPORTIONAL TO KEYLEVER TOUCH Filed June 7, 1967 INVENTOR.

SAMUEL D. CAPPOTTO A G E NT I Nov. 5, 1968 s. D. CAPPOTTO 3,409,111

KEYLEVER TOUCH CONTROL WITH COMPENSATING MEANS DIRECTLY PROPORTIONAL TO KEYLEVER TOUCH Filed June 7, 1967 2 Sheets-Sheet 2 INVENTOR. SAMUEL D. CAPPOTTO AGENT United States Patent KEYLEVER TOUCH CONTROL WITH COMPENSAT- ING MEANS DIRECTLY PROPORTIONAL T0 KEYLEVER TOUCH Samuel D. Cappotto, Syracuse, N.Y., assignor to SCM Corporation, a corporation of New York Filed June 7, 1967, Ser. No. 644,361 6 Claims. (Cl. 197-33) ABSTRACT OF THE DISCLOSURE An adjustable touch control mechanism for varying the force required to depress keylevers in a business machine. The mechanism includes a key operable linkage adjustably connected to a spring means which effects the key depression touch and a spring biased equalizing member operable on the key linkage to reduce the effort required to add tension, in the spring means when increasing the key depression touch.

Background of the invention Most adjustable touch control devices in use employ an adjusting means that is detented between a plurality of positions for moving the spring bail to increase or decrease the tension against the depression of the keylevers. The reason for the detent provision is to retain the adjustor in the selected position as it is influenced by the spring bail tension.

Other well known adjustor-s rely on types of friction to retain the selected adjustor. Either of these methods for retaining the adjustor usually require a reasonably heavy force to move when selection by the operator is desired.

Summary of the invention The object of the present invention is to provide an adjustabletouch control device which employs an equalizing member to compensate for the tension exerted by the spring bail on the adjustor so that the adjustor may be moved with only a light force. The invention also provides the capability of infinite selected positions of the adjustor within its extreme positions.

Description of the drawing FIGURE 1 is a rear perspective view of a typewriter bottom frame, partially cut away to show the components of the invention assembled thereto;

FIGURE 2 is a partial top plan view of the adjustor and the equalizing member when positioned in its extreme light touch position;

FIGURE 3 is a view similar to FIGURE 2 showing the adjustor positioned in its extreme heavy touch position; and

FIGURE 4 is a left elevational view, on an enlarged scale and partially in section, of the front frame portion and a finger piece for operating the touch control mechanism.

Description of the preferred embodiment With reference to FIGURE 1, the invention mainly consists of an equalizing member that is pivotally mounted on the machine frame 12 by a pin 14 and is biased clockwise by a relatively heavy tension spring 16 so that a working surface 18 of the member 10 is held in a mating relationship with a pin 20 that is rigidly mounted on an adjusting lever 22.

The adjusting lever 22, which is pivotally mounted on the frame 12 by a pin 24 is so located with respect to the member 10 and the working surface of the member is of such an angle that the spring 16 causes a counter-clockwise 3,409,111 Patented Nov. 5, 1968 ICE force on the adjusting lever 22 which varies depending on the position of the lever 22. If the lever is pivoted clockwise as shown in FIGURE 2, the member 10 is in turn pivoted counter-clockwise and the working surface 18 of the member 10 is at such an angle relative to the lever 22 that the spring 16 exerts a lesser counter-clockwise force on the lever. On the other hand, if the lever is pivoted counter-clockwise as shown in FIGURE 3, the working surface 18 is at such an angle to the lever that the spring exerts a greater counter-clockwise force on the lever.

This counter-clockwise force on the lever 22 is almost negligible when the adjusting lever is in its extreme light touch position as shown in FIGURE 2 while it is greatest when the adjusting lever is in its extreme heavy touch position as shown in FIGURE 3. When the lever is moved from one extreme to the other, the rate of spring 16 and the angle of the working surface 18 of the member 10 cause this force to either build up at an increasing rate or lessen at a decreasing rate whichever applies to the direction of lever movement, the reason for which will become apparent shortly.

Referring again to FIGURE 1, a link 26 interconnects the lever 22 with a bail connector 28 which is pivotally mounted on a rigid bracket 30 by pins 32. The bail connector 28 has a finger 34 that abuts a tab 36 of a spring bail 38 which is biased clockwise about a frame mounted pivot rod 40 by a plurality of small individual keylever springs 42, only one of which is shown.

When the lever 22 is pivoted counter-clockwise, the keylever springs 42 are tensioned as the spring bail 38 is pivoted counter-clockwise via the bail connector 28 and the link 26. This tensioning of the spirngs 42 increases the resistance against depression of the keylever buttons 44 and thus provides the operator with a heavier touch. By the reverse operation, when the lever 22 is pivoted clockwise, the springs 42 are less-tensioned as the spring bail 38 pivots clockwise and the operator is provided with a lighter touch.

It can now be seen that while the spring bail 38, which is tensioned by the plurality of keylever springs 42, exerts a clockwise force on the lever 22, the member 10 which is tensioned by the spring 16 exerts a counterclockwise force on the lever 22.

The force exerted by the spring bail 38 when the lever 22 is pivoted from its extreme light touch position to its extreme heavy touch position builds up at an increasing rate due to the biasing rate of the combined plurality of keylever springs 42. This rate of force increase is substantially equal to the rate of force increase exerted by the member 10 previously described. Being that these rates are substantially equal and being that they are exerted in opposite directions upon the lever 22, the only force required to pivot the lever 22 in either direction regardless of its position within its limits, is the force required to overcome friction at the various bearing points throughout the device which is substantially negligible.

The lever 22 has an extension 46 which extends to the front of the machine frame, through an elongated slot 48 in the frame and is provided with a finger piece 50 for movement by the operator in either direction to select the desired keybutton touch. A further mechanical advantage for pivoting the lever is evidenced by the length of the lever itself from the finger piece to the pivot 24.

The lever extension 46 is slideably supported by the lever 22 within a pair of lever guides 52 and is lightly biased toward the rear of the machine by a long light tension spring 54 that lies within cooperating slots 56 in the lever 22 and the lever extension 46 and is connected between the two levers. This arrangement provides the lever with a telescoping feature in order to insure that a lip 58 (FIGURE 4) of the finger piece 50 is in constant contact with the outside surface of the frame 12 and that the lever extension moves within the guides 52 as required when the lever 22 is moved by the finger piece.

It can now be seen that the present invention accompliShes its object of providing a touch control mechanism wherein only a light force is required to move the tension adjustor for selecting a desired touch by the employment of a force equalizing member to counter-balance the tension of the spring bail.

It is also evident that the present invention provides a touch control device which has infinite adjustment between its limits and remains in any selected position by providing an adjusting member which is not influenced by the spring bail force when in a selected position.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than from the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. A tensioning device for keylevers in a business machine including a frame (12), a bail (38) movably mounted on the frame, springs (42) interconnecting the keylevers (44) to the bail for holding the keylevers in a normally raised position and an adjusting means for moving the bail in a direction to increase the tension on the springs thereby increasing the force required to depress the keylevers comprising:

(a) a key controllable linkage (50, 22, 26, 28) operable to move the bail in said direction thereby increasing the effort required to operate said key controllable linkage due to increasing the tension of the springs; and

(b) means (10, 16) operable to apply a force on said key controllable linkage at an increasing rate as said linkage moves in said direction thereby substantially compensating for the increasing effort required to operate said key controllable linkage.

2. A tensioning device as defined in claim 1 wherein said last named means includes a spring biased member operable on said key controllable linkage to automatically substantially compensate for the increasing effort required to operate said key controllable linkage.

3. A tensioning device as defined in claim 1 wherein said key controllable linkage includes a lever (22) pivotally supported (24) on the frame near the rear of the machine and extending to the front of the machine having a control key (50) thereon for moving said lever from a first limit to a second limit, said lever having an abutment (20) carried thereon and located near the pivot thereof; and wherein'said last named means includes a member (10) pivotally supported on the frame and having a working surface (18), a' spring (16) connected to said member for biasing said working surface against said abutment in a direction toward said lever pivot to have little biasing effect on said lever when said lever is near said first limit and in a direction away from said lever pivot to increase the biasing effect on said lever when said lever is moved to said second limit.

4. A tensioning device as defined in claim 1 wherein said last named means includes a spring biased member (10) operable on said key linkage (50, 22, 26, 28) to hold said key linkage in any of its operable positions when shifting the bail (38) to various positions.

5. A tensioning device as defined in claim 2 wherein said key controllable linkage includes a lever (22) operable in said direction to move the bail (38) to increase the tension on the springs (42) and wherein said spring biased member (10) engages said lever to bias said lever in said direction at an increasing rate.

6. A tensioning device as defined in claim 1 wherein said key controllable linkage includes a lever (22) operable in said direction to move the bail (38) to increase the tension on the springs (42) and wherein said last named means includes a spring biased member (10) pivotable about a fixed pivot (14) and having a working surface (18) engageable with said lever (22), said working surface being operable to increase its-biasing force on said lever as said lever is moved in said direction by said lever moving toward said pivot of said spring biased member.

References Cited UNITED STATES PATENTS 2,020,223 11/1935 Utz 197-33 2,098,285 11/1937 Gabrielson et al. 197--33 2,148,877 2/ 1939 Rauscher 19733 2,206,624 7/1940 Bates et al. 197-17 2,235,416 3/1941 Bridgwater l97--33 2,624,439 1/1953 Zeamer l9733 2,890,782 6/1959 Stuiber 19733 3,229,798 1/1966 Grasholf 19717 ROBERT E. PULFREY, Primary Examiner.

E. S. BURR, Assistant Exaimner. 

